A method of this kind and an arrangement of this kind is known from DE-OS 36 21 937 (U.S. Pat. No. 5,107,427). There, for fault detection in the area of measured-value detection of an electronic power control, the operating variable of the power control which is detected by a measuring device is influenced. Especially faults in the A/D interfaces or in the channels of a multiplexed A/D converter of the electronic control unit of the power control system can be detected. This fault detection takes place by switching off the ground lead of the position transducer of an accelerator pedal and/or of a throttle flap by means of a switch element actuated by the computing element of the control unit. The position transducer is configured as a potentiometer. If the measured variable detected by the measuring device in the switched-off state exceeds pregiven limit values or limit values derived from the read-in supply voltage of the measuring device, a fault state is recognized.
In several applications, it has been shown that this procedure is not always satisfactory. A control variable of the power control is changed during monitoring. Accordingly, this power control cannot be carried out during the monitoring time.
Furthermore, it has been shown that the monitoring procedure, as a consequence of tolerances in the region of the switching element, the measuring devices as well as the input lines to the control unit, takes considerable time during which the electronic control cannot be carried out (in the range of several 100 milliseconds). Furthermore, additional circuit measures in the area of the switch element are necessary especially with a view toward the resistance to short circuits of the switch element to the battery or supply voltage.